Ventilator-associated pneumonia: The central role of transcolonization

Inhaled Amikacin to Prevent Ventilator-Associated Pneumonia

BACKGROUND

Whether preventive inhaled antibiotics may reduce the incidence of ventilator-associated pneumonia is unclear.

METHODS

In this investigator-initiated, multicenter, double-blind, randomized, controlled, superiority trial, we assigned critically ill adults who had been undergoing invasive mechanical ventilation for at least 72 hours to receive inhaled amikacin at a dose of 20 mg per kilogram of ideal body weight once daily or to receive placebo for 3 days. The primary outcome was a first episode of ventilator-associated pneumonia during 28 days of follow-up. Safety was assessed.

RESULTS

A total of 850 patients underwent randomization, and 847 were included in the analyses (417 assigned to the amikacin group and 430 to the placebo group). All three daily nebulizations were received by 337 patients (81%) in the amikacin group and 355 patients (83%) in the placebo group. At 28 days, ventilator-associated pneumonia had developed in 62 patients (15%) in the amikacin group and in 95 patients (22%) in the placebo group (difference in restricted mean survival time to ventilator-associated pneumonia, 1.5 days; 95% confidence interval [CI], 0.6 to 2.5; P = 0.004). An infection-related ventilator-associated complication occurred in 74 patients (18%) in the amikacin group and in 111 patients (26%) in the placebo group (hazard ratio, 0.66; 95% CI, 0.50 to 0.89). Trial-related serious adverse effects were seen in 7 patients (1.7%) in the amikacin group and in 4 patients (0.9%) in the placebo group.

CONCLUSIONS

Among patients who had undergone mechanical ventilation for at least 3 days, a subsequent 3-day course of inhaled amikacin reduced the burden of ventilator-associated pneumonia during 28 days of follow-up. (Funded by the French Ministry of Health; AMIKINHAL ClinicalTrials.gov number, NCT03149640; EUDRA Clinical Trials number, 2016-001054-17.).

The gut microbiota composition is linked to subsequent occurrence of ventilator-associated pneumonia in critically ill patients

Ventilator-associated pneumonia (VAP) is the most frequent nosocomial infection in critically ill-ventilated patients. Oropharyngeal and lung microbiota have been demonstrated to be associated with VAP occurrence, but the involvement of gut microbiota has not been investigated so far. Therefore, the aim of this study is to compare the composition of the gut microbiota between patients who subsequently develop VAP and those who do not. A rectal swab was performed at admission of every consecutive patient into the intensive care unit (ICU) from October 2019 to March 2020. After DNA extraction, V3-V4 and internal transcribed spacer 2 regions deep-sequencing was performed on MiSeq sequencer (Illumina) and data were analyzed using Divisive Amplicon Denoising Algorithm 2 (DADA2) pipeline. Among 255 patients screened, 42 (16%) patients with invasive mechanical ventilation for more than 48 h were included, 18 (43%) with definite VAP and 24 without (57%). Patients who later developed VAP had similar gut bacteriobiota and mycobiota α-diversities compared to those who did not develop VAP. However, gut mycobiota was dissimilar (β-diversity) between these two groups. The presence of Megasphaera massiliensis was associated with the absence of VAP occurrence, whereas the presence of the fungal genus Alternaria sp. was associated with the occurrence of VAP. The composition of the gut microbiota, but not α-diversity, differs between critically ill patients who subsequently develop VAP and those who do not. This study encourages large multicenter cohort studies investigating the role of gut-lung axis and oropharyngeal colonization in the development of VAP in ICU patients. Trial registration number: NCT04131569, date of registration: 18 October 2019. IMPORTANCE The composition of the gut microbiota, but not α-diversity, differs between critically ill patients who subsequently develop ventilator-associated pneumonia (VAP) and those who do not. Investigating gut microbiota composition could help to tailor probiotics to provide protection against VAP.

Lung microbiome and origins of the respiratory diseases

The studies on the composition of the human microbiomes in healthy individuals, its variability in the course of inflammation, infection, antibiotic therapy, diets and different pathological conditions have revealed their intra and inter-kingdom relationships. The lung microbiome comprises of major species members of the phylum Bacteroidetes, Firmicutes, Actinobacteria, Fusobacteria and Proteobacteria, which are distributed in ecological niches along nasal cavity, nasopharynx, oropharynx, trachea and in the lungs. Commensal and pathogenic species are maintained in equilibrium as they have strong relationships. Bacterial overgrowth after dysbiosis and/or imbalanced of CD4⁺ helper T cells, CD8⁺ cytotoxic T cells and regulatory T cells (Treg) populations can promote lung inflammatory reactions and distress, and consequently acute and chronic respiratory diseases. This review is aimed to summarize the latest advances in resident lung microbiome and its participation in most common pulmonary infections and pneumonia, community-acquired pneumonia (CAP), ventilator-associated pneumonia (VAP), immunodeficiency associated pneumonia, SARS-CoV-2-associated pneumonia, acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD). We briefly describe physiological and immunological mechanisms that selectively create advantages or disadvantages for relative growth of pathogenic bacterial species in the respiratory tract. At the end, we propose some directions and analytical methods that may facilitate the identification of key genera and species of resident and transient microbes involved in the respiratory diseases' initiation and progression.

Exploring the complex relationship between the lung microbiome and ventilator-associated pneumonia

INTRODUCTION

Understanding the presence and function of a diverse lung microbiome in acute lung infections, particularly ventilator-associated pneumonia (VAP), is still limited, evidencing significant gaps in our knowledge.

AREAS COVERED

In this comprehensive narrative review, we aim to elucidate the contribution of the respiratory microbiome in the development of VAP by examining the current knowledge on the interactions among microorganisms. By exploring these intricate connections, we endeavor to enhance our understanding of the disease's pathophysiology and pave the way for novel ideas and interventions in studying the respiratory tract microbiome.

EXPERT OPINION

The conventional perception of lungs as sterile is deprecated since it is currently recognized the existence of a diverse microbial community within them. However, despite extensive research on the role of the respiratory microbiome in healthy lungs, respiratory chronic diseases and acute lung infections such as pneumonia are not fully understood. It is crucial to investigate further the relationship between the pathophysiology of VAP and the pulmonary microbiome, elucidating the mechanisms underlying the interactions between the microbiome, host immune response and mechanical ventilation for the development of VAP.

Ventilator-associated pneumonia is linked to a worse prognosis than community-acquired pneumonia in children

BACKGROUND

Around 12-20% of patients with community-acquired pneumonia (CAP) require critical care. Ventilator-associated pneumonia (VAP) is the second cause of nosocomial infection in Paediatric Intensive Care Units (PICU). As far as we know, there are no studies comparing both types of pneumonia in children, thus it remains unclear if there are differences between them in terms of severity and outcomes.

OBJECTIVE

The aim was to compare clinical and microbiological characteristics and outcomes of patients with severe CAP and VAP.

METHODS

A retrospective descriptive study, including patients diagnosed of VAP and CAP, with a positive respiratory culture and under mechanical ventilation, admitted to the PICU from 2015 to 2019.

RESULTS

238 patients were included; 163 (68.4%) with CAP, and 75 (31.5%) with VAP. Patients with VAP needed longer mechanical ventilation (14 vs. 7 days, p<0.001) and more inotropic support (49.3 vs. 30.7%, p = 0.006). Patients with VAP had higher mortality (12 vs. 2.5%, p = 0.005). Enterobacterales were more involved with VAP than with CAP (48 vs. 9%, p<0.001). Taking into account only the non-drug sensitive microorganisms, patients with VAP tended to have more multidrug-resistant bacteria (30 vs. 10.8%, p = 0.141) than patients with CAP.

CONCLUSION

Patients with VAP had worse prognosis than patients with CAP, needing longer mechanical ventilation, more inotropic support and had higher mortality. Patients with VAP were mainly infected by Enterobacterales and had more multidrug resistant microorganisms than patients with CAP.

RISK score for developing ventilator-associated pneumonia in children: The RISVAP study

OBJECTIVES

Ventilator-associated pneumonia (VAP) is the second most common healthcare-associated infection in children. The aim of this study was to determine the risk factors for VAP in children and to create a risk score for developing VAP (RISVAP score).

STUDY DESIGN

It was a prospective observational study, including children who required mechanical ventilation (MV), registered in the multicentre ENVIN-HELICS database from 2014 to 2019. The regression coefficients of each independent risk factor for VAP were used to create the RISVAP score. Each factor scored 0 if it was absent, or, if it was present, an assigned value from 1 to 7, according to the regression coefficient.

RESULTS

A total of 3798 patients were included, 97(2.5%) developing VAP. The independent risk factors for VAP were: female (odds ratio [OR]: 1.642, p = 0.024), MV > 4 days (OR: 26.79, p < 0.001), length in pediatric intensive care unit > 7 days (OR: 11.74, p < 0.001), and previous colonisation (OR: 4.18, p < 0.001). The RISVAP was calculated for each patient as the sum of all the independent risk factors. Three risk groups were obtained: low (0-5 points), intermediate (6-12 points), and high risk for VAP (13-16 points). The area under the curve for the final score was 0.905 (95%confidence interval: 0.888-0.923, p < 0.001).

CONCLUSIONS

The RISVAP is the first risk score for VAP in pediatric populations. Using this predictive score, might be helpful to detect vulnerable patients and therefore implement preventative strategies.

A retrospective evaluation of multiple definitions for ventilator associated pneumonia (VAP) diagnosis in an Australian regional intensive care unit

BACKGROUND

Ventilator Associated Pneumonia is a common complication of invasively ventilated patients with significant and underestimated morbidity and mortality. Defining VAP cases is greatly varied as many definitions are used with varying success and sensitivity. This study evaluates VAP detection using four definitions in a regional Australian Intensive Care Unit (ICU).

METHODS

A cohort of patients admitted to ICU at the Mackay Base Hospital from April 1st 2020 to March 31st 2021, who had endo-tracheal intubation and mechanical ventilation for longer than 48 h were identified. Each patient was examined across four common definitions of VAP. Head-to-head analysis of definitions was pursued to determine the most suitable definition. The four definitions used included: An Australian VAP definition, the CDC VAP definition, the Mackay Base Hospital Local Protocol and a Physician Decision Arm.

RESULTS

66 unique patients and 2 re-intubations were identified during the data collection window. The local protocol identified 8 cases of VAP. The Australian VAP definition identified 6 additional cases and 0 missed cases compared to the local protocol. The CDC definition missed 4 cases and identified 4 additional cases compared to the local protocol. Finally, the physician arm identified 10 cases including 8 additional cases and missed 6 cases.

CONCLUSIONS

VAP is an extremely difficult clinical condition to define and detect. Definitions have varied accuracy and suffer logistically for application to the individual patient. Refined criteria for diagnosis of VAP is greatly needed and its prevalence in intensive care units likely remains uncertain.

Risk Factors and Nursing Countermeasures of Ventilator-Associated Pneumonia in Children in the Intensive Care Unit

Objective

This study discussed and analyzed the risk factors and nursing countermeasures of ventilator-associated pneumonia (VAP) in the children intensive care unit (ICU).

Methods

In this study, 155 children with mechanical ventilation in the pediatric intensive care unit from Oct. 2018 to Oct. 2020 were chosen as research objects. We retrospectively analyzed the clinical data of children and divided them into VAP groups and non-VAP groups according to the occurrence of VAP. Subsequently, we adopted a univariate and multivariate logistic regression model to analyze and clarify the risk factors of VAP and formulated the corresponding nursing countermeasures.

Results

49 cases of total research objects had occurred VAP, with an infection rate of 31.62%. The primary pathogenic bacteria were Gram-negative bacteria (43/70, 61.43%). According to multivariate logistic regression analysis, the duration of mechanical ventilation, invasive procedures, and application of hormones and antacids are all independent risk factors for VAP in pediatric ICU. The VPA group had longer hospital stay than the non-VAP group, and the difference was statistically significant ((20.92 ± 4.16)d, (15.24 ± 3.77)d, t = 8.4383, P ≤ 0.001). The hospitalization cost of the VPA group was substantially higher than that of the non-VAP Group ((45.8 ± 10.4) thousand Yuan, (33.2 ± 4.3) thousand Yuan, t = 10.6822, P ≤ 0.001).

Conclusion

Children admitted to the pediatric ICU have a high VAP incidence. The primary pathogenic bacteria are Gram-negative bacteria. As the occurrence of VAP is closely related to a variety of factors, we should take targeted nursing countermeasures to reduce the duration of mechanical ventilation and the frequency of invasive operations and use the hormone and antacids rationally to reduce the risk of VAP and improve the prognosis.

Probiotics in the Intensive Care Unit

The understanding of the gut microbiome in health and disease has shown tremendous progress in the last decade. Shaped and balanced throughout life, the gut microbiome is intricately related to the local and systemic immune system and a multitude of mechanisms through which the gut microbiome contributes to the host’s defense against pathogens have been revealed. Similarly, a plethora of negative consequences, such as superinfections and an increased rate of hospital re-admissions, have been identified when the gut microbiome is disturbed by disease or by the iatrogenic effects of antibiotic treatment and other interventions. In this review, we describe the role that probiotics may play in the intensive care unit (ICU). We discuss what is known about the gut microbiome of the critically ill, and the concept of probiotic intervention to positively modulate the gut microbiome. We summarize the evidence derived from randomized clinical trials in this context, with a focus on the prevention of ventilator-associated pneumonia. Finally, we consider what lessons we can learn in terms of the current challenges, efficacy and safety of probiotics in the ICU and what we may expect from the future. Throughout the review, we highlight studies that have provided conceptual advances to the field or have revealed a specific mechanism; this narrative review is not intended as a comprehensive summary of the literature.

Systematic skin and nasal decolonization lowers Staphylococcus infection in pediatric cardiac surgery

BACKGROUND

Postoperative infections occur in approximately 10% of pediatric cardiac surgeries, involving Staphylococcus species in most cases. Nasal decontamination of Staphylococcus with mupirocin has been reported to reduce postoperative Staphylococcus infections after cardiac surgery in adults, but the effect of preoperative decontamination in children undergoing cardiac surgery has not been sufficiently studied to reach consensus.

METHODS

We conducted a single-center retrospective study to evaluate the impact of systematic preoperative decolonization with intranasal mupirocin application and skin-washing with chlorhexidine soap on postoperative Staphylococcus infection in children undergoing cardiac surgery. Our population was divided into three groups according to decolonization protocol (group N: no decolonization; group T: targeted decolonization in Staphylococcus aureus [SA] carriers only; and group S: systematic decolonization).

RESULTS

A total of 393 children were included between October 2011 and August 2015 (122 in group N, 148 in group T, and 123 in group S). The Staphylococcus infection rate significantly decreased in group S compared to group N (0.8% vs. 7.7%; p < 0.05) and tended to decrease in group S compared to group T (0.8% vs. 4.7%; p = 0.06). Systematic decontamination also significantly reduced the rate of infections starting from the skin (including surgical site infections and bloodstream infections) compared to targeted decolonization or lack of decolonization, but had no effect on the rate of pulmonary infections.

CONCLUSION

The results of our study suggest that systematic preoperative skin and nasal decontamination, regardless of SA carriage status, could reduce the rate of postoperative Staphylococcus infections after cardiac surgery in children.

Effect of Breast Milk Oral Care on Mechanically Ventilated Preterm Infants: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

The benefits of breast milk oral care in mechanically ventilated preterm infants remain controversial. This study aimed to systematically review the evidence on the benefits of breast milk oral care in mechanically ventilated preterm infants.

METHODS

The randomized controlled trials of breast milk oral care for mechanically ventilated preterm infants were searched in EMBASE, PubMed, Cochrane Library, Web of Science, WANFANG Date and China National Knowledge Infrastructure databases. The retrieval language was limited to Chinese and English, and the final search was conducted until March 2022. Outcome measures included ventilator-associated pneumonia (VAP), mechanical ventilation time (MVT), length of stay (LOS), necrotizing enterocolitis (NEC), late-onset sepsis, mortality during hospitalization, time of full intestinal feeding and time of full oral feeding. Two researchers independently screened the literature, extracted the data, and conducted the literature quality assessment. Meta-analysis was mainly performed using RevMan 5.3.

RESULTS

Eight articles involving 1,046 preterm infants were included. Our meta-analysis showed that compared with the control group, breast milk oral care could reduce the incidence of VAP [RR = 0.41, 95% CI (0.23, 0.75), P = 0.003] and NEC [RR = 0.54, 95% CI (0.30, 0.95), P = 0.03], and shorten the MVT [MD = -0.45, 95% CI (-0.73, -0.18), P = 0.001] and LOS [MD = -5.74, 95% CI (-10.39, -1.10), P = 0.02]. There were no significant differences in the mortality during hospitalization [RR = 0.94, 95% CI (0.67, 1.33), P = 0.74], the incidence of late-onset sepsis [RR = 0.79, 95% CI (0.40, 1.59), P = 0.51], the time of full intestinal feeding [MD = -2.42, 95% CI (-5.37, 0.52), P = 0.11] and the time of full oral feeding [MD = -3.40, 95% CI (-10.70, 3.91), P = 0.36] between the two groups.

CONCLUSIONS

Oral care of breast milk can reduce the incidence of VAP and NEC, shorten MVT and LOS in mechanically ventilated preterm infants. However, due to the quality and quantity limitations of the included studies, larger sample size and more strictly designed clinical trials are still needed in the future to further confirm the findings of this study.

Impact of Healthcare-Associated Infections Connected to Medical Devices-An Update

Healthcare-associated infections (HAIs) are caused by nosocomial pathogens. HAIs have an immense impact not only on developing countries but also on highly developed parts of world. They are predominantly device-associated infections that are caused by the planktonic form of microorganisms as well as those organized in biofilms. This review elucidates the impact of HAIs, focusing on device-associated infections such as central line-associated bloodstream infection including catheter infection, catheter-associated urinary tract infection, ventilator-associated pneumonia, and surgical site infections. The most relevant microorganisms are mentioned in terms of their frequency of infection on medical devices. Standard care bundles, conventional therapy, and novel approaches against device-associated infections are briefly mentioned as well. This review concisely summarizes relevant and up-to-date information on HAIs and HAI-associated microorganisms and also provides a description of several useful approaches for tackling HAIs.

The microbiota in pneumonia: From protection to predisposition

Mucosal surfaces of the upper respiratory tract and gut are physiologically colonized with their own collection of microbes, the microbiota. The normal upper respiratory tract and gut microbiota protects against pneumonia by impeding colonization by potentially pathogenic bacteria and by regulating immune responses. However, antimicrobial therapy and critical care procedures perturb the microbiota, thus compromising its function and predisposing to lung infections (pneumonia). Interindividual variations and age-related alterations in the microbiota also affect vulnerability to pneumonia. We discuss how the healthy microbiota protects against pneumonia and how host factors and medical interventions alter the microbiota, thus influencing susceptibility to pneumonia.

An overview of guidelines for the management of hospital-acquired and ventilator-associated pneumonia caused by multidrug-resistant Gram-negative bacteria

PURPOSE OF REVIEW

Multidrug-resistant (MDR) Gram-negative pathogens in hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are associated with poor clinical outcomes. These pathogens represent a global threat with few therapeutic options. In this review, we discuss current guidelines for the empiric management of HAP/VAP caused by MDR Gram-negative pathogens.

RECENT FINDINGS

The incidence of MDR Gram-negative bacteria is rising among cases of nosocomial pneumonia, such that it is now becoming a significant challenge for clinicians. Adherence to international guidelines may ensure early and adequate antimicrobial therapy, guided by local microbiological data and awareness of the risk factors for MDR bacteria.

SUMMARY

Due to the increasing prevalence of HAP/VAP caused by MDR Gram-negative pathogens, management should be guided by the local ecology and the patient's risk factors for MDR pathogens. The main risk factors are prior hospitalization for at least 5 days, prior use of broad-spectrum antibiotics, prior colonization with resistant pathogens, admission to hospital settings with high rates of MDR pathogens, and septic shock at the time of diagnosis with nosocomial pneumonia.

Oral Microbiome and SARS-CoV-2: Beware of Lung Co-infection

The new coronavirus SARS-CoV-2, the cause of COVID-19, has become a public health emergency of global concern. Like the SARS and influenza pandemics, there have been a large number of cases coinfected with other viruses, fungi, and bacteria, some of which originate from the oral cavity. Capnocytophaga, Veillonella, and other oral opportunistic pathogens were found in the BALF of the COVID-19 patients by mNGS. Risk factors such as poor oral hygiene, cough, increased inhalation under normal or abnormal conditions, and mechanical ventilation provide a pathway for oral microorganisms to enter the lower respiratory tract and thus cause respiratory disease. Lung hypoxia, typical symptoms of COVID-19, would favor the growth of anaerobes and facultative anaerobes originating from the oral microbiota. SARS-CoV-2 may aggravate lung disease by interacting with the lung or oral microbiota via mechanisms involving changes in cytokines, T cell responses, and the effects of host conditions such as aging and the oral microbiome changes due to systemic diseases. Because the oral microbiome is closely associated with SARS-CoV-2 co-infections in the lungs, effective oral health care measures are necessary to reduce these infections, especially in severe COVID-19 patients. We hope this review will draw attention from both the scientific and clinical communities on the role of the oral microbiome in the current global pandemic.

Reduction of Health Care-Associated Infections (HAIs) with Antimicrobial Inorganic Nanoparticles Incorporated in Medical Textiles: An Economic Assessment

Health care-associated infections (HAIs) affect millions of patients annually with up to 80,000 affected in Europe on any given day. This represents a significant societal and economic burden. Staff training, hand hygiene, patient identification and isolation and controlled antibiotic use are some of the standard ways to reduce HAI incidence but this is time consuming and subject and subject to rigorous implementation. In addition, the lack of antimicrobial activity of some disinfectants against healthcare-associated pathogens may also affect the efficacy of disinfection practices. Textiles are an attractive substrate for pathogens because of contact with the human body with the attendant warmth and moisture. Textiles and surfaces coated with engineered nanomaterials (ENMs) have shown considerable promise in reducing the microbial burden on those surfaces. Studies have also shown that this antimicrobial affect can reduce the incidence of HAIs. For all of the promising research, there has been an absence of study on the economic effectiveness of ENM coated materials in a healthcare setting. This article examines the relative economic efficacy of ENM coated materials against an antiseptic approach. The goal is to establish the economic efficacy of the widespread usage of ENM coated materials in a healthcare setting. In the absence of detailed and segregated costs, benefits and control variables over at least cross sectional data or time series, an aggregated approach is warranted. This approach, while relying on some supposition allows for a comparison with similar data regarding standard treatment to reduce HAIs and provides a reasonable economic comparison. We find that while, relative to antiseptics, ENM coated textiles represent a significant clinical advantage, they can also offer considerable cost savings.

OmpK36-mediated Carbapenem resistance attenuates ST258 Klebsiella pneumoniae in vivo

Carbapenem-resistance in Klebsiella pneumoniae (KP) sequence type ST258 is mediated by carbapenemases (e.g. KPC-2) and loss or modification of the major non-selective porins OmpK35 and OmpK36. However, the mechanism underpinning OmpK36-mediated resistance and consequences of these changes on pathogenicity remain unknown. By solving the crystal structure of a clinical ST258 OmpK36 variant we provide direct structural evidence of pore constriction, mediated by a di-amino acid (Gly115-Asp116) insertion into loop 3, restricting diffusion of both nutrients (e.g. lactose) and Carbapenems. In the presence of KPC-2 this results in a 16-fold increase in MIC to Meropenem. Additionally, the Gly-Asp insertion impairs bacterial growth in lactose-containing medium and confers a significant in vivo fitness cost in a murine model of ventilator-associated pneumonia. Our data suggests that the continuous selective pressure imposed by widespread Carbapenem utilisation in hospital settings drives the expansion of KP expressing Gly-Asp insertion mutants, despite an associated fitness cost.

Carbapenem-resistance in Klebsiella pneumoniae sequence type ST258 can be enhanced by modification of the porins OmpK35 and OmpK36. Here, Wong et al. solve the crystal structure of a clinical ST258 OmpK36 variant, elucidating the mechanism of resistance and consequences on pathogenicity in vivo.